1. Field of the Invention
The present invention relates to high frequency devices and, in particular, to a high frequency device provided with a rectangular waveguide tube that is capable of transmitting high frequency signals.
2.  Description of the Related Art
Conventionally, a high frequency device that is capable of transmitting high frequency signals using rectangular waveguide tubes is known. For example, Japanese Patent Laid-open publication No. 2004-221718 discloses a high frequency device that is capable of transmitting high frequency signals, in which two metallic plates are joined and a plurality of rectangular waveguide tubes are formed on the joint surface.
In this type of high frequency device, forming a groove on at least one metallic plate is necessary to make a rectangular waveguide tube. In this regard, it is required to process the metallic plate to be a complex shape, which makes manufacturing the device difficult.
In addition, the high frequency device having joined metallic plates has problems such as being heavy, and requiring an additional high frequency circuit board for processing signals being transmitted through the waveguide tube. Furthermore, there can be a problem that thickness of the device is increased when the high frequency board is laminated to the metallic plates.
Since the metallic plates cannot be joined using an adhesive, the metallic plates are joined using screws. Therefore, it is necessary to secure space for the screws, which makes the scale of the device increase.